REGEXP_FILE
  RegExpPatternImpl: <(a|b|c|d|e)f>
    RegExpBranchImpl: <(a|b|c|d|e)f>
      RegExpGroupImpl: <(a|b|c|d|e)>
        PsiElement(GROUP_BEGIN)('(')
        RegExpPatternImpl: <a|b|c|d|e>
          RegExpBranchImpl: <a>
            RegExpCharImpl: <a>
              PsiElement(CHARACTER)('a')
          PsiElement(UNION)('|')
          RegExpBranchImpl: <b>
            RegExpCharImpl: <b>
              PsiElement(CHARACTER)('b')
          PsiElement(UNION)('|')
          RegExpBranchImpl: <c>
            RegExpCharImpl: <c>
              PsiElement(CHARACTER)('c')
          PsiElement(UNION)('|')
          RegExpBranchImpl: <d>
            RegExpCharImpl: <d>
              PsiElement(CHARACTER)('d')
          PsiElement(UNION)('|')
          RegExpBranchImpl: <e>
            RegExpCharImpl: <e>
              PsiElement(CHARACTER)('e')
        PsiElement(GROUP_END)(')')
      RegExpCharImpl: <f>
        PsiElement(CHARACTER)('f')